Hot coffee and fires in winter good for both gardens and gardeners

If you are not already on a plane to a tropical destination, you are likely staying put this winter with a hot cup of coffee in front of the fireplace.

My friend Brenda McIntyre was doing just that when she sent a text and asked, whether it was alright to put wood ash from her fireplace into the composter?

“Is once-in-a-while OK?” she asked. “Maybe it will balance off all the acidic coffee grounds I add every day? The Calgary soil is higher pH, so is this useful?”

I was thrilled Brenda was asking about wood ash. Many people throw it away. What a waste! Or they sprinkle it on their soil. What a mess!

As Brenda mentioned, soils in Calgary are already high in pH. This means they are alkaline, and that is not good for plants – it makes them struggle for nutrients because the soil won’t part with elements as easily when the pH is high. The average soil pH in Calgary is around eight, yet plants prefer 6.5 to seven on a scale of one to 14 where one is sulfuric acid and 14 is baking soda alkaline.

The best place for wood ash is in an outdoor compost because it is a naturally acidic place and the veggies and frequent coffee grounds contribute to that.

Coffee grounds are high in nitrogen but acidic, so they are also better in compost. In fact, my daughter Chelsie’s worms attempted suicide when she added too many coffee grounds all at once to her worm bin. The worms were plotting their escape and trying to climb out of the composter in her basement when they dried up and died.

Luckily, my daughter spotted the first pale flat skins, all that was left of the lifeless worms, the morning after she added a deep layer of coffee grounds and it wasn’t too late to save the rest of the bin by adding more neutral food waste.

The beauty of a compost pile is it takes very acidic materials, such as coffee, blends them with the highly alkaline materials such as wood ash, runs them though the guts of micro-organisms and creates a nice, somewhat-acidic mix perfect for our gardens.

So I suggested to Brenda that she add wood ash to the compost pile.

A nice cup of coffee and a warm fire, repurposed for our gardens by running the leftovers through a compost, is the perfect way to think spring. Like the food we feed ourselves – food that goes to benefit our plants also needs some preparation.

Donna Balzer is a garden writer and speaker. Check out her blog at or follow her on twitter @NoGuffGardener.